JPS6112400B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preferred method for manufacturing a hybrid multilayer circuit board that can integrally form a partially laminated structure of a flexible circuit board and a rigid circuit board.

Various methods are known for increasing component mounting density by configuring a rigid circuit board into a multilayer structure. Connecting with a flexible circuit board accurately satisfies various requirements such as simplifying the connection method within a limited space, improving component mounting density, high reliability, and low cost. The need for this is even greater now.

Therefore, as a method for the simple purpose of simply attaching a flexible circuit board to a rigid circuit board that has been manufactured separately in advance, it is basically possible to simply attach a flexible circuit board to a rigid circuit board that has been manufactured separately in advance. Even if processing is possible, the resulting product cannot be expected to exceed the circuit wiring capacity of each board, so a partial multilayer structure using these two circuit boards that can obtain a synergistic effect from both is necessary. is strongly desired. Therefore, a major problem that must be solved in order to achieve a hybrid circuit board with such a partially multilayered structure is how to ensure mutual conduction between circuit patterns on the inner layer or between this and the outer layer. In particular, the conventional through-hole plating method applied when multiple circuit boards are uniformly multilayered cannot be used as is as a method for making such a structure conductive, and other special methods are required. Even if suitable conduction means have been proposed, these methods complicate the process and increase costs, and the results obtained are extremely uncertain, making it difficult to adopt them in mass production processes. It is extremely difficult to mass produce hybrid multilayer circuit boards that can be appropriately adopted for various specifications.

The basic purpose of the present invention is to arbitrarily realize the necessary conduction between each circuit pattern in a multi-layered structure in a series of steps, and to create flexible circuit boards and rigid circuit boards. An object of the present invention is to provide a method for manufacturing a hybrid multilayer circuit board in which a desired number of circuit boards can be partially and integrally stacked on each other.

The drawings show one embodiment of the invention.
FIG. 6 conceptually illustrates the manufacturing process of a flexible circuit board in which a required circuit pattern is formed on only one side. The material on which the conductor layers 2 and 3 are formed, such as copper foil, is cut to the required size,
A predetermined through hole 4 is formed in this material, and the entire material is subjected to a through hole plating process in order to provide a through hole plating 5 to the hole 4. Next, as shown in FIG. 1, 2, after plating inspection and pretreatment are performed as appropriate, resist layers 6 and 7 are formed on both sides to an appropriate thickness, and the required circuit pattern is formed as shown in FIG. 1, 3. An exposed film (not shown) prepared in advance in order to correspond to the above is placed on one side while being aligned with the through-hole hole 4, and after a full exposure process is performed on both sides, the unexposed parts are developed with a developer and removed. and leave the necessary parts 6A and 6B. After subjecting the thus obtained product to appropriate pattern inspection and correction processing as necessary, the whole is subjected to etching processing, and as shown in FIG. 1, a required circuit pattern 2A, 2B, and then the remaining resist layers 6A and 6B and the resist layer 7 on the back side.
By peeling off, it is possible to form a circuit pattern 2A having through-hole plating 5 and another pattern 2B without it, as shown in FIG. 1. In addition, if necessary, an insulating surface coating layer 8 is laminated on this pattern-formed surface using a material such as a coverlay via an adhesive 9 except for the terminal portion 10 as shown in FIGS. 1 and 2. .

In this way, first, as shown in FIG. Adhesive material 15 is appropriately applied to the outer periphery of the pattern area including the multilayered area 12 represented by line 11 as shown by diagonal lines. On the other hand, as shown in FIG. 3, a hard substrate 16 having the same size as the base film 1 and having a conductive layer such as copper foil on only one side in this embodiment is prepared.
An elongated through hole 19 is bored at the boundary line between the multilayer region 17 and the non-multilayer region 18, which are indicated by imaginary lines on the hard substrate 16 side corresponding to the multilayer region 12 and the non-multilayer region 14, respectively. Then, by aligning these mutual areas and laminating the pattern area of the flexible circuit board so that the conductor layer 20 of this board 16 appears on the surface as shown in FIG. Except for the non-multilayer regions 14 and 18, other parts including the multilayer regions 12 and 17 are joined. At this stage, the through holes 19 provided in the substrate 16 are preferably filled with adhesive resin 19A. Therefore, in this multilayer region 17, a through-hole hole 21 is formed from the conductor layer 20 of the hard substrate 16 so as to penetrate the circuit pattern 2B as shown in the figure.
is installed through the hole, and through-hole plating 22 is applied thereto as appropriate. Next, as shown in FIG. 4, resist layers 23 and 24 are formed on both sides to an appropriate thickness, and
Exposure films (not shown) prepared in advance are stacked on each surface while being aligned with the through-holes 4 and 21, and the entire surface is exposed and developed, and unnecessary portions are removed as shown in FIG. 4. This was etched and the required circuit patterns 20A and 20B were formed on the substrate 16 side as shown in FIG. 4, and circuit patterns 3A and 3B were formed on the other side of the flexible circuit board, respectively. Resist layers 23A, 23
When B, 24A, and 24B are removed, the multilayer region 12 (17) in this embodiment is formed as shown in FIG.
, the plating 5 of one through-hole hole 4 brings electrical continuity between the circuit patterns 2A and 3A of the flexible circuit board, and the plating 2 of the other through-hole hole 21
A multilayer structure can be obtained in which the circuit pattern 2OB of the rigid circuit board 2 is electrically connected to the circuit patterns 2B and 3B of the flexible circuit board. If necessary, it is possible to provide a surface coating layer 26 on the patterns 3A and 3B surfaces of the flexible circuit board using an appropriate adhesive 25, as shown in FIG. 4, as described above.

After completing each of the above steps, the laminate is punched out into a desired shape by trimming or the like along both division lines 11 and 13 in FIG. 2. Since the non-multilayer region 14 (18) is not in a bonded state, the non-multilayer region 18 of the hard substrate 16 in this region is separated by the through hole 19.
Because adhesive 1 falls off easily, in multilayer areas, the hard circuit board and part of the flexible circuit board
5 and 6 can be obtained, and in the non-multilayered region, a hybrid multilayer circuit board with an integral structure as shown in FIGS. 5 and 6 consisting only of a flexible circuit board can be obtained immediately. In this multilayer region, as described above, the circuit pattern between the two circuit boards can be suitably made conductive and realized through a series of steps. Here, the resin 19A filled in the through hole 19 protects the circuit pattern surface located on the inner layer of the flexible circuit board during the processing of each process of FIG. After the hybrid circuit board is completed as shown in Figure 6, it is fixed with appropriate flexibility and the mechanical strength of the adjacent portion of the flexible circuit board to the multilayer area is improved as shown in the figure. It can be improved.

As is clear from the cross-sectional view of FIG. 6, in the above embodiment, a rigid circuit board having circuit patterns 20A and 20B only on one surface is used as opposed to a flexible circuit board having required circuit patterns on both sides. However, by forming the required circuit patterns 27A and 27B in advance on the surface of the rigid substrate 16 corresponding to the bonding surface with the flexible circuit board in the preliminary stage of FIG. As a result, it is possible to manufacture a hybrid multilayer circuit board with a multilayer region having a four-layer circuit pattern as shown in FIG. Moreover, by adopting the above method, one flexible circuit board 3 as illustrated in FIG.
0, different hard circuit boards 31 and 32 are multi-layered on arbitrary parts of the front or back surface of the hard circuit board 32 while ensuring necessary through-hole conduction, and one of them, for example, at the end of the hard circuit board 32 is It is also possible to similarly bond a portion of another flexible circuit board 33 to one side or the other side in a multilayer manner.

As described above, according to the present invention, when achieving a partial multilayer structure between a flexible circuit board and a rigid circuit board, the corresponding multilayer region is at least selectively bonded, and this part is bonded. It is possible to process the necessary electrical conductivity in a consistent process, and also to selectively provide through holes at the adjacent boundary between the required multilayered region and the non-multilayered region that does not join in each step of the multilayered structure. By this, unnecessary parts that were not bonded in the non-multilayered area after punching out the desired shape in the final process are removed, thereby making it possible to create a flexible circuit board that is integrated with the multilayered area and is only a flexible circuit board. A hybrid multilayer circuit board having a non-multilayer region can be easily manufactured with high precision. In particular, according to the present invention, a through-hole means is provided in a predetermined shape in a hard circuit board portion corresponding to the boundary between the multilayer region and the non-multilayer region as a separation means, and an adhesive is used in the non-multilayer region. By adopting a method that does not use , for example, complex products such as multiple multilayer circuit boards spaced apart like islands can be arranged arbitrarily and integrally on a flexible circuit board can be constructed very easily. There is. Therefore, a hybrid circuit board with a partial multilayer structure of circuit boards with different characteristics, such as a flexible circuit board and a rigid circuit board, can be manufactured with uniform quality and excellent characteristics through a consistent process. products can be manufactured in one piece, and the necessary mutual conduction in the required circuit patterns within such a multilayered structure is also significantly simplified, greatly increasing component mounting ability. The resulting hybrid multilayer circuit board can be provided at low cost.

[Brief explanation of the drawing]

Figures 1 to 6 are explanatory diagrams of each process for forming a required circuit pattern on one side of a flexible circuit board in the present invention, and Figure 2 is an illustration of bonding to the multilayer area of the flexible circuit board. 3 is a conceptual plan view illustrating the manner in which the material is provided; FIG. 3 is a diagram illustrating the step of providing a through hole at the boundary between the corresponding multilayer region and the non-multilayer region on the hard substrate side; FIGS. 4 1 to 6 5 is an explanatory diagram of each process in which a flexible circuit board and a rigid board are laminated to form the required circuit pattern on each surface and to achieve the necessary conduction in the multilayer area. A conceptual perspective view of a hybrid multilayer circuit board according to an embodiment of the present invention obtained by the method shown in FIGS. 4 to 4, FIG. 6 is a conceptual enlarged sectional view of FIG. FIG. 8 is a conceptual enlarged sectional view of a hybrid multilayer circuit board according to another embodiment. FIG. 8 is a conceptual perspective view showing another application example of a hybrid multilayer circuit board obtained by employing the present invention. 1...Base film, 2A, 2B...Circuit pattern, 5...Through hole plating, 12...Multilayer region, 14...Non-multilayer region, 16...Hard substrate, 19...Through hole, 19A... ...Filled resin, 22
...Through hole matsuki.

Claims (1)

[Claims] 1. A predetermined through hole is drilled in the base film from which the flexible circuit board is to be obtained, the hole is plated with through holes, and a required circuit pattern is formed on one side of the base film in relation to the through hole. After forming an adhesive layer on the multilayered region of this circuit pattern, the circuit pattern is aligned while a hard substrate having through holes is aligned along the corresponding boundary line between the multilayered region and the non-multilayered region. The hard substrate is laminated on the side and the through holes are filled with resin, and then the necessary through holes are drilled in the multilayer area of this hard substrate and the through holes are plated. Other required circuit patterns are formed on the surface of the multilayer region and the other surface of the base film in relation to the two through-holes, and finally these flexible circuit boards and rigid circuit boards are formed. Punching the laminate into a predetermined product shape formed by the multilayer region and the non-multilayer region having no adhesive layer while intersecting both ends of the through hole, and detaching the hard substrate in the non-multilayer region. In this way, a multilayer region is formed of both flexible and rigid circuit boards and has through-hole conduction between their required circuit patterns, and a non-multilayer region is formed only of flexible circuit boards. A method for manufacturing a hybrid multilayer circuit board characterized by: